I tend to use very little Lemon as I find too much will mask the flavour of the fish. If you want a subtle lemon flavour just half a lemon and rub it over the fish.
As far as getting as much off a fish as possible there are a couple of ways. Good filleting, which will only come by lots of practice or for the very easy way, cook it in the oven, very loosely wrapped in foil so it will steam in it's own juices. Add whatever you like as flavouring such as Lemon, Garlic or herbs. I quite like Corriander with mine but not too much as it can take away from the subtle flavour of the fish. When the fish is cooked, place it on a warmed plate and eat it with a fork and your fingers. You will find that it is so tender it will fall off the bone and the skin can be removed very easily.
Jim.